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The influence of trypanosomiasis on African animal production


Trypanosomiasis - often referred to as tryps - is a disease of humans and animals carried by the tsetse fly. It has been a serious constraint to agricultural development and human settlement in Africa since the turn of the century. At that time most countries of the continent had low-level populations of both humans and livestock, and the main method of combating the disease was to confine settlement to either non-infested areas or those of low tsetse density. Consequently, conflicts occurred, particularly in the event of the human disease, when the presence of tsetse flies prevented the utilization of high-potential resource areas.

Since then increasing populations and the growing demand for land and food has been forcing human beings into closer contact with the tsetse fly. Today, apart from areas with high tsetse density, most of sub-Saharan Africa has been populated and there has been a shift from the control of sleeping sickness - the main symptom of trypanosomiasis in humans - to the containment of animal trypanosomiasis.

Tsetse-transmitted trypanosomiasis is classified as severe in the majority of the 37 sub-Saharan countries affected, where it figures among the first three priority veterinary diseases. Despite this fact and the concerted and specific action taken since the early 1960s, the pattern of disease incidence remains much the same, in some areas even having increased through attempts to utilize tsetse-infested areas for increasing populations. The situation may deteriorate further as national efforts decline because of shrinking resources and because donor assistance may be re-orientated away from the livestock sector.

Although primarily a human and veterinary health problem, the task of trypanosomiasis control is complicated by the need to direct operations against the tsetse vector and by the diminishing armoury of effective drugs, the most recent of which were produced some 30 years ago.

Criticism of the use of insecticides for vector control has recently directed efforts to the revival of fly-attractive devices (traps, targets, screens). The potential of these simple devices for cost-effective control through community participation has been demonstrated.

However, trypanosomiasis control or eradication is but one element in the attainment of optimal agricultural production and it is essential that decision-makers take into account the implementation of appropriate farming systems and land husbandry practices to achieve natural resource conservation and long-term sustainability. This achievement together with the establishment of a justifiable programme approach to tsetse control across the continent, depends on the mobilization of international support, national commitment and livestock owner participation. Efforts are also needed to quantity the precise effects of tsetse and trypanosomiasis on agricultural production systems from an economic and social point of view. The alternative is to continue the shorter-term approach adopted in the past and which, despite large investments, has barely influenced the level of constraint over the long term.

It was Churchill who said, "Give us the tools and we will finish the job". In the context of trypanosomiasis, adequate 'tools" have been available for some time but the "job'' has hardly begun.

The FAO Animal Health Service, responsible for African animal trypanosomiasis control, has recently sought international expert advice on a revised policy that will place considerations for control firmly where they belong, i.e. at a high priority level.

It is recognized that increased efforts are needed to provide a more accurate and composite picture of the effects of demographic changes on land-use patterns and demand. The destruction of the tsetse's habitat, resulting from increased fuelwood demand, has also been recognized. Conversely, the conversion of rangeland into cropland may force livestock into closer contact with the tsetse.

Observations indicate that, in the face of increasing demand for land, the tsetse/trypanosomiasis situation is dynamic in most areas while efforts to contain the disease and, more importantly, to strive toward sustainable animal agricultural systems require a more comprehensive approach than that adopted so far.

FAO is seeking to adjust its policy to this changing situation through the strengthened coordination of activities and an in-depth evaluation of the justification for disease and vector control. The end result should eventually ensure that the available 'tools" are effectively and concertedly applied to disease control, land use and increased agricultural production, and hence to the alleviation of poverty in African rural communities.

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